package chapter_20


trait Abstract {
  // 20.1
  type T
  def transform(x: T): T
  val initial: T
  var current: T
}


class Concrete extends Abstract {
  // Abstract的具体实现需要对每种抽象成员填入定义
  type T = String
  def transform(x: String) = x + x
  val initial = "hi"
  var current = initial
}


object chapter_20 {

}
